Sun blisters vs. HSV

Hey there,

I've recently been tested for HSV, and came up negative in both type I and II, about a month ago.   I was out in the sun about 3 days ago, and got sunburnt terribly.  Today I woke up and my lips were swollen, and blistered.  Is this a repercussion from the sun or a manifestation of a possible HSV infection?  What's the difference between a coldsore and potential blistering from the sun?

Thanks.

[gracefromHHP]

even the best blood tests still miss 1 out of every 10 hsv1 infections. the best thing to do is to be seen today and ask them to do a pcr swab on your lips and inside your mouth to see if herpes is detected or not.

grace